The irreplaceable role of surviving megafauna in long-distance seed dispersal: Evidence from an experiment with Neotropical mammals
Data files
May 27, 2024 version files 88.55 KB
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RawData_Revised_Giombini_et_al._2024.xlsx
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README.md
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Abstract
The downsizing of disperser assemblages by selective defaunation is a worldwide phenomenon thought to have important consequences in animal-dispersed plants. Numerous large-seeded Neotropical plants currently depend on the last megafaunal survivors, the large tapirs Tapirus spp., and medium-sized frugivores. The extent to which medium frugivores are functionally equivalent to tapirs remains unresolved. We combined feeding trials, seed dispersal kernel modeling based on seed retention times and animal movement simulation (Levy walks), and germination experiments in a large-seeded palm to assess the dispersal quality provided by the largest (tapirs) and two medium (foxes and howler monkeys) frugivore species in terms of dispersal distances and gut passage effects on germination. Tapirs retained the seeds in the gut for much longer (mean=221 hours) than howlers (43 h) and foxes (22 h). Median dispersal distance by tapirs (1252 m) was 14 and 40 times larger than that by foxes (88 m) and howlers (31 m), respectively. The seed dispersal kernel of tapirs showed a 5th percentile value (291 m) larger than the 95th percentiles of foxes (285 m) and howlers (108 m). Manually depulped and gut-passed seeds germinated in similar proportions, showing, respectively, 3.5 and 2.5―2.9 times higher values than intact fruits. Germination probability and seed viability decreased with retention time in howlers’ and tapirs’ gut, with howlers showing a steeper negative relationship. Such detrimental effect implies a trade-off between germination success and dispersal distance. We conclude that tapirs may not play a unique role in germination enhancement but move seeds much further than medium frugivores, thus playing a critical role as long-distance dispersers of many plants. This study provides important insights on palm–frugivore interactions and the potential consequences for large-seeded plants of losing the last megafaunal representatives in the Neotropics.
https://doi.org/10.5061/dryad.3j9kd51sv
Data on seed retention time in the gut of three frugivores (Cerdocyon thous, Alouatta caraya and Tapirus terrestris) and germination outcomes obtained by feeding trials and germination experiments, respectively (Associated Article: doi: 10.1111/oik.10488)
Description of the data and file structure
Raw data is presented in an excel file.
Column headings and definition of variables:
1. Seed.ID: Identification of each seed. Those named as 01.NA to 25.NA were only used in feeding trials for estimating seed retention times, but not in germination experiments.
The data frame is ordered by Seed.ID
2. Treatment: Pre-sowing treatment applied to each seed. Intact: fruits retaining the pulp; Depulped: fruits which pulp was artificially removed; Depulped.soaked: depulped fruits that were then submerged in water until the next day (for comparison against tapirs that defected in water pools); Fox, Howler, Tapir: seeds retrieved from fox (Cerdocyon thous), howler (Alouatta caraya), and tapir (Tapirus terrestris) feces, respectively.
3. Individual: Identification of the individual of each frugivore species (whenever possible)
4. Mother.palm: The mother palm from which the fruit (seed) was collected (i.e. maternal source)
5. SRT.Low_(hours): The lower limit of each seed retention time as an interval-censored observation (i.e. the earliest possible seed release time resulting from our monitoring scheme), measured in hours.
6. SRT.Upp_(hours): The upper limit of each seed retention time as an interval-censored observation (i.e. the latest possible seed release time resulting from our monitoring scheme), measured in hours.
7. Germination: Germination occurrence or failure during the experiment, coded as 1 or 0, respectively.
8. Viability_TZ.Test: Seed viability at the end of the germination experiments, assessed by means of the Tetrazolium test. This was evaluated for 25.5% of all seeds that had not germinated at the end of the experiments. V: Viable, NV: Not viable, NA: Not tested.
Other details:
In all cases, "NA" denotes Not Available datum.
"Inf" indicates infinite for the upper limit of seed retention time (interval-censored data) in cases which we were confident that the seed had not been released before the last examination of feces (i.e. it represents a "right-censored" observation). Most non-recovered seeds, however, were assumed to have been missed at some point during the period of feces examination.
Code/Software
Statistical analyses of this data were conducted by using the R software. The complete R code for these analyses, as well as ready-to-use input files for R, are given as accompanying text files.
Data on seed retention time was collected from feeding trials and seed recovery. Data on germination was obtained from germination experiments performed in a greenhouse.
- Giombini, Mariano Ignacio et al. (2024), The irreplaceable role of surviving megafauna in long-distance seed dispersal: Evidence from an experiment with Neotropical mammals, , Article, https://doi.org/10.5281/zenodo.11263666
- Giombini, Mariano Ignacio et al. (2024), The irreplaceable role of surviving megafauna in long-distance seed dispersal: Evidence from an experiment with Neotropical mammals, , Article, https://doi.org/10.5281/zenodo.11263667
- Giombini, Mariano Ignacio et al. (2024), The irreplaceable role of surviving megafauna in long-distance seed dispersal: Evidence from an experiment with Neotropical mammals, , Article, https://doi.org/10.5281/zenodo.11506896
- Giombini, Mariano I.; Pésole, Diana; Benítez, Anuncio Daniel et al. (2024). The irreplaceable role of surviving megafauna in long‐distance seed dispersal: evidence from an experiment with Neotropical mammals. Oikos. https://doi.org/10.1111/oik.10488